1. Field of the Invention
The present invention relates to a data recording method for recording information on a phase-change rewritable optical disc, and more particularly, to a data recording method for allowing mass production of optical discs which are subjected to high-quality formatting processing. The invention also pertains to a device and method for formatting phase-change optical discs, and a phase-change optical disc formatted by this method. The invention also relates to a method and a device for recording rewritable recording media, and to optical recording media on which data is recorded by this method. The invention also pertains to a write protection method for optical discs.
2. Discussion of the Related Art
For formatting a magneto-optical (MO) disk, an MO disk drive for recording and playing back information to and from the MO disk detects defective sectors on the disk, registers them on a primary defect list (PDL), and records the PDL on the disk. Accordingly, when a subsequent recording or playback operation is performed, the MO disk drive re-allocates the defective sectors. By virtue of the defective-sector re-allocating function provided for the MO disk drive by the use of the PDL, formatted MO disks can be mass-produced.
In contrast, an optical disc drive, such as a compact disc rewritable (CD-RW) drive, for recording and playing back phase-change optical discs, such as CD-RW discs, cannot detect defective sectors or perform re-allocating processing on the defective sectors.
Thus, an application program (hereinafter simply referred to as an “application”) for controlling the operation of an optical disc drive detects errors, for example, recovered errors, read errors, and write errors, and perform re-allocating processing.
Such an application is usually executed by using a predetermined computer system provided outside the optical disc drive, and thus, the processing time is increased over that required for executing the MO-disk formatting processing.
Additionally, execution start conditions and determination conditions to determine whether the re-allocate processing is to be performed and specific processing contents are dependent on the application. It is thus difficult to mass-produce optical discs which are subjected to formatting processing compatible with a plurality of types of applications.
Formatted discs are recorded or played back in drives produced by different manufacturers. It is thus necessary to ensure the signal quality in an area which is unambiguously used for a playback operation, for example, in an area in which file structures or application data are recorded. However, the overwriting characteristics of optical discs using a phase change material, such as CD-RW discs, are different according to the linear recording speed. Concerning multi-speed CD-RW discs in which x1-, x2-, or x4-recording is possible, if x4-overwriting is performed after initially performing x4-recording, jitter is increased in the recording signal in the above-described area. If x2-overwriting is performed after initially performing x2- or x4-recording, an increase in jitter is almost negligible. When formatting CD-RW discs by using an application (packet writing software, such as DirectCD, PacketCD, or abCD), the overwriting of the file structure or the application data is performed after the recording layer of the disc is completely formatted (initial recording). The discs formatted as described above are not suitable for mass production, and also, jitter becomes larger in the area in which the file structure or the data application is recorded than in the format area, resulting in a lower-quality recorded signal. Thus, such discs cannot be played back by another drive.
As an optical-recording-media recording method, a packet writing method is known in which a track is divided into precise fixed-length units, which are referred to as “packets”, and recording, erasing, and random access can be performed on data in units of packets.
As phase-change optical recording media, CD-RWs in which data can be overwritten about 1000 times by using such a packet writing method are particularly known.
It is necessary that the phase-change optical recording media using the packet writing method be formatted before being used. After being formatted, each fixed-length packet consists of 32 blocks, each block having 2048 bytes. Each packet sequentially includes from one end of the block: one link block, which partitions the packet from the adjacent packet; four run-in blocks indicating the head of user data; user-data description blocks in which user data is recorded; and two run-out blocks indicating the end of the data. In the optical recording medium, in addition to the above-described physical format, disc-volume control information, recordable final address, route directory information, and so on, are recorded.
Link block data “0 ” is recorded in the link block. The link block data “0 ” is generated by a drive controller of an optical recording device, and is added to user data temporarily stored in a buffer, thereby forming a fixed-length packet. The fixed-length packet is then recorded in the optical recording medium (optical disc).
In the packet writing method, user data stored in the user-data description block is overwritten in units of packets, and the link block data is also written simultaneously with the overwriting of the user data.
In this case, when writing new user data into the optical recording medium in which old user data is stored, as indicated by (a) of FIG. 10, the link block data “0 ” used for writing the old user data is written into the link block, as indicated by (b) and (c) of FIG. 10.
However, when the same link block data “0 ” is always written into the same physical position before and after writing the user data, physical noise is accumulated in the link block of the recording medium, thereby increasing the jitter.
Particularly in a recording medium, such as in a database, in which user data is frequency overwritten, the same link block data is written into the same link block every time user data is overwritten, thereby increasing the jitter. As a result, the optical recording medium cannot be overwritten any longer before maximum overwriting operations are performed.
Generally, in a disc housed in a cartridge, such as a floppy disk or an MO disk, it is possible to determine when the disk is loaded on a drive whether the disk is write-protected by a write protection mechanism disposed on the cartridge, thereby protecting files from being inadvertently erased or overwritten.
In contrast, a disc which is not housed in a cartridge, such as a CD-RW disc, mechanical write protection means are not provided, and thus, it is difficult to protect data from being erased or overwritten in a CD-RW disc.
In CD-RW discs, packet writing software, such as DirectCD (manufactured by Adaptec) using the universal disc format (UDF), PacketCD (manufactured by Cequadrat), B'sClip (manufactured by BHA), is known. In this software, fixed packet writing is used for CD-PW discs. By using fixed packet writing, data can be randomly overwritten or erased by being recorded or erased in units of packets. Accordingly, data can be easily recorded on CD-RW discs, as in floppy disks or MO disks.
However, as discussed above, since a write protection function is not provided for current CD-RW discs or packet writings software, a user may erroneously overwrite, erase, or format CD-RW discs. As a result, important data may be lost.